Modelling of alarm handling responses times: A case of the Ladbroke Grove rail accident in the UK

The purpose of the paper was to address the timeliness of the signaller’s intervention in the Ladbroke Grove rail incident in the UK, as well as to consider the utility of human performance time modeling more generally. Human performance response time modeling is a critical area for Human Factors and Ergonomics research. This research applied two approaches to the same problem, to see if they arrived at the same conclusion. The first modeling approach used the Alarm Initiated Activity (AIA) model. This approach is useful for indicating general response times in emergency events, but it cannot comment in detail on any specific case. The second modeling approach employed a multi-modal Critical Path Analysis (CPA) technique. The advantage of the latter approach is that it can be used to model a specific incident on the basis of the known factors from the accident inquiry. The results show that the AIA model produced an estimated response time of 17 seconds whereas the CPA model produced an estimated response time of 19 seconds. This compares with the actual response time of the signaller of 18 seconds. The response time data from both approaches are concordant and suggest that the signaller’s response time in the Ladbroke Grove rail accident was reasonable. This research has application to the modeling of human responses to emergency events in all domains. Rather than the forensic reconstruction approach used in this paper, the models could be used in a predictive manner, to anticipate how long human operators of safety-critical systems might take to respond in emergency scenarios